There are many instances wherein a welder performs welding operations in cold climates. Conventional welding shields are provided with viewing apertures which allow generally straight forward vision of a welder, but the lower margin of the viewing aperture is not sufficiently depressed downwardly to enable a welder who wears bifocal glasses to view his work in an unobstructed manner through the lower portions of his bifocal lenses. As a result, the welder must pivot his shield downwardly in order that the lower marginal edge of the viewing aperture may be sufficiently depressed to enable him to view his work through the lower portions of his bifocals. While this is not very troublesome in warm climates, downward pivoting of a shield in this manner by a welder wearing bifocal glasses in cold climates results in the viewing window being downwardly displaced into registry with the air being exhaled through the welder's nostrils. Inasmuch as air being exhaled is quite moist, the warmer content of the exhaled air tends to condense on the inner surface of the light filtering panel. Of course, condensation on the inner surface of the light filtering panel severely limits the vision of the welder.
Although some welding helmets are provided with viewing apertures whose lower marginal edges are sufficiently depressed to enable welders wearing the helmets to view their welding operation through the lower portions of bifocal lenses worn by the welder, these vertically elongated viewing windows are also subjected to the formation of condensation on the inner surfaces thereof in cold climates due to moist air being exhaled from the nostrils of the welder.
Accordingly, a need exists for an improved viewing window in a welder's helmet which will enable a welder to view close welding operations through the lower portions of bifocal lenses worn by the welder and without lower portions of the viewing window of the helmet being in registry with moist air being exhaled from the nostrils of the welder.
Examples of conventional and slightly modified welder's helmets including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 2,103,006, 2,487,848, 2,598,265, 2,628,530, 2,668,951, 2,784,410, 2,817,087 and 2,973,522.